I received my stand-alone residence card in early November. I wrote to them to ask why they failed to return my passport with the residence sticker inside, and It turns out the UKBA LOST MY PASSPORT. They notified me of their failure to locate my passport in late November, and I had to go to the US Embassy in London to get a new one. UKBA assured me over the phone that I can travel abroad with the residence card (stand alone document) and the new passport, as long as the personal details (name, etc) remain the same. I insisted the UKBA provide me with a document which assured me that I may safely travel abroad without getting hassled at customs upon returning to the UK. I also spoke to an immigration lawyer about this and he recommended that I travel with certified photocopies of relevant UKBA letters, marriage certificate and other documents which prove I have a right to live in the UK, and travel with those documents rather than the originals. You can get certified photocopies made at selected Post Office locations in the UK, at present it costs £7 for 3 pages of photocopies and you must provide your own copies for them to certify.

I traveled to Spain last weekend and upon my return my passage through customs (I went through the 'European passports' area) was completely trouble-free. I only showed my new passport and the stand-alone travel document (aka residence card).

The fact that UKBA lost my passport is abhorrent and I think they actually misplaced it in April and were stringing me along hoping it would turn up. I think when I got my MP involved, they began to realise they need to address my case, and it was only then they sent me the letter in November apologising for losing my passport.

I should note that UKBA has since located my passport (now invalid) and some of the documents that were with it. They returned the docs, but couldn't return the passport as I had already reported it lost to the US Embassy. What a pain.